Isolation amplifiers are commonly employed to transfer a signal from one part of an electrical or electronic system to another part which is electrically isolated from the first part. An example of such a system is a high-voltage power supply containing batteries whose voltage must be monitored. In such systems, there is typically a battery voltage sensing circuit and a separate circuit to drive an operator display which displays the value of the battery voltage. As a safety precaution, the sensing circuit is electrically isolated from the display circuit, so that an operator is unlikely to contact hazardous voltages even if a fault should develop in the sensing circuit. An isolation amplifier enables the output of the sensing circuit to be transferred across an isolation barrier to the display circuit while maintaining the necessary electrical isolation.
Many systems employing isolation amplifiers have stringent requirements for accuracy. For example, in the monitoring system described above, it is important that the battery voltage is accurately measured and displayed. Therefore the isolation amplifier used in such a system must operate accurately.
The accuracy of any amplifier, including isolation amplifiers, is a critical parameter affecting its design, operation, and cost. Generally, achieving high accuracy requires the use of high-precision electronic components, which are more expensive than lower-precision components. To reduce the cost of electrical systems employing isolation amplifiers, it is desirable to build an inexpensive isolation amplifier with high accuracy.